Conventionally, various smoke sensors have been proposed that can determine the type of smoke, including not only smoke from a fire but also smoke from cooking, steam in a bathroom and the like. For example, Patent Document 1 discloses a smoke sensor using a plurality of light emitting devices with different wavelengths. This smoke sensor includes: a light-emitting device that emits a light having a relatively short wavelength toward an environment in which smoke may exist (e.g., blue light-emitting diode (LED)); a light-emitting device that emits a light having a relatively long wavelength toward the environment (e.g., near-infrared light-emitting diode (LED)); and one light-receiving device provided at a location in which the lights emitted from these light-emitting devices are not directly received. Then, this smoke sensor causes the light-emitting devices to emit lights at timings different from each other, obtains the amounts of received lights from the light-receiving device that receives the lights scattered by smoke, and determines the type of the smoke based on the obtained amounts of received lights.